1. Technical Field
The present invention relates to ball support assemblies, such as those which are provided in floors of cargo carriers to provide low friction rolling support for cargo.
2. Background Art
There are in the prior art cargo handling systems where the support surface for the cargo has a plurality of ball support units positioned across the floor. The ball member of each such unit is rotatably mounted in a manner to provide a low friction support surface over which the cargo can roll. In some instances, the ball members are spring loaded in their respective units so as to provide for limited up and down movement of the ball members, so that the loads can be properly distributed over a number of ball units.
Such cargo handling systems have been used in connection with aircraft where fast and convenient cargo handling is required, and the cargo handling must be accomplished in a relatively limited space. While such cargo handling systems in the past have been used effectively, there is a continuing need to improve the design of these systems relative to cost, convenience of installation and repair, and overall effectiveness of operation.
There are a number of such ball support units which are shown in the patent literature, and these are discussed below.
U.S. Ser. No. 631,804, Manley, shows a ball caster, where there is a main support ball held in position by an open ring and supported at least partly by a second smaller ball member.
U.S. Pat. No. 1,963,956, Craig, illustrates a ball transfer unit for a cargo system, where a ball member is mounted on ball bearings, and there is a semi-circular lock spring to hold the unit in place.
U.S. Pat. No. 2,617,509, Britton, discloses a roller assembly where there is a cylindrically shaped roller mounted for rotation about a horizontal axis. The roller is urged by a lower compression spring to an upper position.
U.S. Pat. No. 2,972,162, Townsend, illustrates a system of load bearing balls where the smaller ball bearings that support the main support ball are mounted in an endless track.
U.S. Pat. No. 3,096,536, Rabelos, shows a ball caster unit where the ball support is mounted in a retainer housing and is urged by a compression spring outwardly to its support position.
U.S. Pat. No. 3,132,904, Wakamatsu et al, illustrates a device for rollably supporting a ball, where there is a particular arrangement of bearing members positioned at selected locations.
U.S. Pat. No. 3,466,697, Cain et al, shows a ball transfer or caster unit where there is a ball supported by a plurality of ball bearings, and held in place by a member having an inwardly extending retaining ring which fits over the ball. A compression spring urges the ball and the member on which it is mounted upwardly to its support position.
U.S. Pat. No. 3,478,382, Nosenzo, shows an arrangement for a ball transfer unit that is generally similar to the Cain et al patent noted above.
U.S. Pat. No. 3,557,401, Jenkins, shows a caster unit where the main ball is supported by a plurality of smaller ball bearings that are arranged in cages so that these can rotate in endless paths, thus preventing jamming.
U.S. Pat. No. 3,739,894, Hinman, shows a ball transfer unit where the main ball is supported by a plurality of smaller ball bearings. The support member has an upper in turned shoulder to hold the main ball in place. There is a compression spring which urges the ball upwardly toward its upper support position. There is a lower frusto-conical member to provide a bottom support for the main ball.
French Pat. No. 1,150,429 shows a ball support unit where there is a main support ball supported by a plurality of smaller bearings, with the bearings being retained in a cage.
French Pat. No. 1,297,185 shows another ball support unit where the main support ball is held by a plurality of smaller bearing members. The main support ball is retained in its position in the unit by a retaining member that extends around an upper portion of the ball.
It is an object of the present invention to provide a ball support assembly particularly adapted for use in cargo handling systems, with the assembly having a desirable balance of features, relative to simplicity and effectiveness of design, and also ease of installation and repair. Other desirable features of the present invention will become apparent in the detailed description that follows.